1. Field of the Invention
The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device which can minimize the number of delay devices to delay a discharging time by a preset period of time, and a method of driving the same.
2. Discussion of the Related Art
Generally, a liquid crystal display device displays images by controlling light transmittance of liquid crystal cells on the basis of video signals. Particularly, an active matrix type LCD device (hereinafter, referred to as “AM LCD device”) is suitable for displaying moving images because the AM LCD device includes switching elements formed in liquid crystal cells respectively. Typically, the switching elements are formed of thin film transistors TFT, as shown in FIG. 1.
Referring to FIG. 1, the AM LCD device converts digital input data to analog data voltages with reference to a gamma reference voltage, supplies the analog data voltages to data lines DL, and supplies scan pulses to gate lines GL, at the same time.
The thin film transistor TFT is provided with a gate electrode, a source electrode and a drain electrode. The gate electrode of thin film transistor TFT is connected to the gate line GL, the source electrode thereof is connected to the data line DL, and the drain electrode thereof is connected to a pixel electrode of liquid crystal cell Clc and one electrode of storage capacitor Cst. Also, a common electrode of liquid crystal cell Clc is supplied with a common voltage Vcom.
The storage capacitor Cst is charged with a data voltage applied from the data line DL when the thin film transistor TFT is turned-on, thereby maintaining a voltage of liquid crystal cell Clc at a constant level.
When the scan pulse is applied to the gate line GL, the thin film transistor TFT is turned-on, whereby a channel is formed between the source and drain electrodes. Thus, the voltage of data line DL is supplied to the pixel electrode of liquid crystal cell Clc. As an alignment in liquid crystal molecules of the liquid crystal cell Clc is changed by an electric field between the pixel electrode and the common electrode, there is a modulation of incident light passing therethrough.
The related art liquid crystal display device including pixels of the aforementioned structure discharges remaining charges from the pixels by using a discharging circuit (not shown) when the supply of power-source voltage VCC is stopped. After the supply of power-source voltage is stopped, the discharging circuit supplies a gate high voltage VGH to the gate line GL for a preset period of time, thereby discharging the remaining charges of pixels through the data line DL. The discharging circuit maintains the supply time of gate high voltage VGH at a constant period of time by using a plurality of low-capacitance capacitors (for example, about 15 low-capacitance capacitors).
The related art liquid crystal display device includes the discharging circuit provided with about 15 low-capacitance capacitors. Accordingly, the related art liquid crystal display device has an increasing fabrication cost and a complicated circuit structure.